Friction braxe



July 12, 1932 c. c. MCMULLIN FRICTIN BRAKE Filed May 17, 1950 L//Y Inventor llorney fill/lill Patented `lduly 12, 1932 STATES @HYDE C. MCMULLIN, OIF LON LME, 'WASHINGTN FRICTIN BEAM .application tiled May i7,

My resent invention relates to improvements 1n friction'brakes of the type adapted for use upon wheels of automotive vehicles, in connection with the brake drums carried with the wheels. ln connection with the drum l utilize an inner, expanding-double-cam disk and a pair of complementary brake shoes for applying the frictional Contact to the drum, and the parts areso combined as to assure a maximum friction surface in the brake with a minimum of power expended for applying the brake.

The invention consists in certain novel combinations and arrangements of parts as will hereinafter be more fully set forth and claimed. In the accompanying drawing l have illustrated one complete example of the physical embodiment of my invention wherein the parts are combined and arranged according to the best mode l have thus far devised for the practical application of the principles of my invention.

Figure 1 is a sectional view of the brake at line l-l of Figure et, with the brake rem" teased.

Figure 2 is a view similar to Figure l,

. with the brake applied.

Figure 3 is an inner face view of tue brake device, showing the stationary tubular axle and part of a rear shaft of an automobile 1n section. t

Figure 4 is a transverse sectional view at line 3l-4 of Figure 3.

Figure 5 is a detail sectional view of the 85 brake actuating cam, as at line 5-5 of Figure 1.

In order that the general arrangement and relation of parts may readily be understood I have shown the journal end of the rear shaft 1 of an automotive vehicle, together with a portion of a disk wheel 2 with its flanged hub 3 to which the usual type of brake drum 4 is firmly 'secured to revolve with the wheel.

.The rear shaft is journaled in the usual tubular, non-rotary axle 5, and the end of the axle is fashioned with a bearing cup 6 for the roller bearing 7 between the journal and the axle. p

At the inner open side of the brake drum,

but

1930. Serial No. 453,191.,

and supported on the tubular axle is a circular plate 8 that is attached as by rivets or bolts to the Harige 9 of the axle, and this plate, which is provided with an open center to fit over the bearing cup, is utilized to support the working parts of the brake within the drum.

A brake operating disk 10 having two complementary cams 10aa, and a pair of radial shoulders 11, together with a center bearing ring 12 about the open center of the disk is mounted to turn slightly on the plate. As an anti-friction device, and to maintain the proper relation between the revolving or oscillatable disk and the stationary bearing cup G of the tubular shaft, l provide a ball bearing 13 between these parts so that a minimum expenditure of power is required for turning the cam disk when the brake is to be applied. y

rlhe turning movement of the disk is limited by the use of a pair of arcuate slots 14 in the disk and pins 15 that are secured to the plate 8 and project through the slots.

rl`he operating disk is turned through the instrumentality of an actuating cam or eccentric l that turns within a circular opening 17 in the disk, the eccentric or cam being in frictional contact with the wall of the circular opening.

rFhe camA is mounted on a shaft 18 that is eccentrically arranged in the opening of the disk and journaled in theplate 8, with a return spring 18a coiled about the shaft with one end engaging the plate and-the other end engaging a link or crank arm 19 that is fixed on the end of the shaft. By means of a brake rod 20 pivoted to the crank arm, and suitable connections, (either manually or mechanically operated) the crank arm is swung to turn the shaft in the application of the brake shoes 21 and 22.

These brake shoes, which are provided with linings 23, areA located between the inner periphery of the brake drum and the cam faces 10a of the cam disk, and the brake shoes have each an inner cam face as 24 complementary to the cam faces 10a of the disk.

The shoes are slightly less than 180 degrees, so that a slight space exists between ends of adjoining shoes when the letter ere expended to brakin position in Figure 2, sind eter the disk is reeesed e pair oi springs 25 drew the shoes together to position of Figure l Where the ends of the two shoes en ege the shoulders of the dislg. The springs tus normeily hold these ends against the shoulders to prevent chattering end to assure that the disk when itis turned will expend the shoes Without, lost motion..

Each shoe is fashioned with e rediel slot 2li and e retaining end guide pin 27, on ehe plate, passes through the slot, end guides the outward end inward movement; oi the shoeo As thus described sind illustrated it will he apparent that l here provided e quick acting hreke device having e maximum friction sur face and utilizing only a minimum in expenditure ont power for applying the brake.

Having thus fully described my invention, what l claim es new sind desire to secure by Letters Patent is The combination with e breite drum and stationery plate, of en oscillatehle, slotted, dish having s pair of opposed peripheral K coms iiormin diametricelly extending shoul ders, oi e pair of slotted lorehe shoes het/'ing angular ends complementary to seid shoulders, guide pins on the plete for the slotted disk and slotted hrelre shoes, seid shoes heving outer friction :feces for engagement with the drum end inner cem. feces complementary to the disk-cerne, springs connecting adjoining ends of the shoes for holding them in contant and :for holding the shoes in Contact with the shoulders when the shoes are retracted, e cern shaft journsled in the plete 4end disposed eceentricelly in e eircuier openinp of 'the disk, e eem on the shaft for feo-ection with the Wells of the opening, sind ineens for turning the shaft.,

testimony Whereei l my signature,

CLYBE C, MoMlJLL/llh hemel-e 

